Search for: All records

Freezing rain events, which have caused billions of dollars in damage in recent decades, are still one of the least understood forms of precipitation. These events affect both urban and rural regions, including cities and forests. However, the often short-lived and sporadic occurrence of these events poses significant challenges to accurate reporting, complicating analysis attempting to fill this knowledge gap. Through the utilization of ERA5 reanalysis from 1979 to 2020 as a proxy for lacking ground truth data, freezing rain events were identified and analyzed throughout eastern North America. These events were then sorted into full area and subarea regimes through a multivariate self-organizing map (SOM) analysis. This classification of regimes and their subsequent analysis showed the varying importances of the initial synoptic states of each event and provide examples of distinct synoptic structures associated with freezing rain events impacting different regions of eastern North America. In addition, our regime classification identified the prevalence of extreme events associated with each regime. This SOM approach can also be configured to more regional scales to provide more granularity to specific regions of eastern North America. 

Abstract Heavy precipitation events and their associated flooding can have major impacts on communities and stakeholders. There is a lack of knowledge, however, about how stakeholders make decisions at the subseasonal-to-seasonal (S2S) time scales (i.e., 2 weeks to 3 months). To understand how decisions are made and S2S predictions are or can be used, the project team for “Prediction of Rainfall Extremes at Subseasonal to Seasonal Periods” (PRES 2 iP) conducted a 2-day workshop in Norman, Oklahoma, during July 2018. The workshop engaged 21 professionals from environmental management and public safety communities across the contiguous United States in activities to understand their needs for S2S predictions of potential extended heavy precipitation events. Discussions and role-playing activities aimed to identify how workshop participants manage uncertainty and define extreme precipitation, the time scales over which they make key decisions, and the types of products they use currently. This collaboration with stakeholders has been an integral part of PRES 2 iP research and has aimed to foster actionable science. The PRES 2 iP team is using the information produced from this workshop to inform the development of predictive models for extended heavy precipitation events and to collaboratively design new forecast products with our stakeholders, empowering them to make more-informed decisions about potential extreme precipitation events.